bvaughn

// This is an advanced example! It is not typically required for application code.
// If you are using a library like Redux or MobX, use the container component provided by that library.
// If you are authoring such a library, use the technique shown below.

// This example shows how to safely update subscriptions in response to props changes.
// In this case, it is important to wait until `componentDidUpdate` before removing a subscription.
// In the event that a render is cancelled before being committed, this will prevent us from unsubscribing prematurely.

// We also need to be careful about how we handle events that are dispatched in between
// `getDerivedStateFromProps` and `componentDidUpdate` so that we don't put stale values into the `state`.

bvaughn

// This is an example of how to fetch external data in response to updated props,
// If you are using an async mechanism that does not support cancellation (e.g. a Promise).

class ExampleComponent extends React.Component {
  _currentId = null;

  state = {
    externalData: null
  };

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

staltz

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

---

This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

---

adilapapaya

Example code for exporting data in a table to a csv file.

subfuzion

Install with Homebrew

brew install mongodb

Set up launchctl to auto start mongod

$ ln -sfv /usr/local/opt/mongodb/*.plist ~/Library/LaunchAgents

/usr/local/opt/mongodb/ is a symlink to /usr/local/Cellar/mongodb/x.y.z (e.g., 2.4.9)

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

mislav

Pagination 101

Article by Faruk Ateş, [originally on KuraFire.net][original] which is currently down

One of the most commonly overlooked and under-refined elements of a website is its pagination controls. In many cases, these are treated as an afterthought. I rarely come across a website that has decent pagination, and it always makes me wonder why so few manage to get it right. After all, I'd say that pagination is pretty easy to get right. Alas, that doesn't seem the case, so after encouragement from Chris Messina on Flickr I decided to write my Pagination 101, hopefully it'll give you some clues as to what makes good pagination.

Before going into analyzing good and bad pagination, I want to explain just what I consider to be pagination: Pagination is any kind of control system that lets the user browse through pages of search results, archives, or any other kind of continued content. Search results are the o